This invention relates to a wind-turbine having a hub carrying a wing which is fitted with a controllable spoiler on its suction side.
The spoiler is immediately actuated by air pressure to initiate a stall in the case of maximum speed and/or shaft torque of the wind-turbine. The European Patent Application No. 0283730 describes an inflatable and stretchable diaphragm to vary the profile contour along the entire chord length, hence influencing the lift of an air foil or a hydrofoil. In principle this type of diaphragm could locally form a sharp edge trip required to initiate a stall if the diaphragm would be much shorter than the chord length. The disadvantage would be a required high air pressure and an overstretched diaphragm. In addition, by retracting the sharp edge the diaphragm creeps back contacting the wing contour, thus producing friction and wear.
It is further known from the German disclosure DE-OS 28 44 262 to actuate immediately a spring biased flap type spoiler by ram air force from outside of the wing. The flap is mounted inside the wing tip. The enduring ram air has the disadvantage of plugging the flap chamber with dirt particles. In addition, the ramming produces a high drag. By these means so far, only the overspeed may be roughly reduced but not a possible overtorque.